package cn.kingshion.juc.locks;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * 生产者消费者案例  Lock
 * 使用 Condition 进行线程之间的通信
 */
public class ProductAndConsumerTestForLock {

    public static void main(String[] args) {
        Clerk clerk = new Clerk();

        Productor productor = new Productor(clerk);
        Consumer consumer = new Consumer(clerk);

        new Thread(productor, "生产者A").start();
        new Thread(consumer, "消费者B").start();
        new Thread(productor, "生产者C").start();
        new Thread(consumer, "消费者D").start();
    }
}

/**
 * 生产者
 */
class Clerk {
    private int product = 0;

    private Lock lock = new ReentrantLock();
    private Condition condition = lock.newCondition();

    // 进货
    public void get() {
        lock.lock();
        try {
            while (product >= 1) {
                System.out.println("产品已满！");

                // 当产品已经满了就开始停止生产者线程
                try {
                    condition.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

            }
            System.out.println(Thread.currentThread().getName() + ":" + (++product));

            condition.signalAll();
        } finally {
            lock.unlock();
        }
        // 注意这里使用 while 可以防止虚假唤醒，如果选择使用 if 可能会导致虚假唤醒，


    }

    // 卖货
    public void sale() {
        lock.lock();
        try {
            while (product <= 0) {
                System.out.println("缺货！");

                //
                try {
                    condition.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

            }
            System.out.println(Thread.currentThread().getName() + ":" + (--product));

            condition.signalAll();
        } finally {
            lock.unlock();
        }
    }
}

/**
 * 生产者
 */
class Productor implements Runnable {
    private Clerk clerk;

    public Productor(Clerk clerk) {
        this.clerk = clerk;
    }

    @Override
    public void run() {
        for (int i = 0; i < 20; i++) {
            clerk.get();
        }
    }
}

/**
 * 消费者
 */
class Consumer implements Runnable {
    private Clerk clerk;

    public Consumer(Clerk clerk) {
        this.clerk = clerk;
    }

    @Override
    public void run() {
        for (int i = 0; i < 20; i++) {
            clerk.sale();
        }
    }
}

